In a recent interface device, forced or contacted feedback called haptic feedback is provided to a user. A haptic version of, for example, a joystick, a mouse, a game pad, a steering wheel, or other devices can output force to a user on the basis of an interaction or an event occurred in a graphic environment of a game or other application programs.
Meanwhile, a touch pad which is formed into a small square shape and provided at a mobile terminal can sense a position of a pointing object with various sensing techniques, such as a capacitive sensor and a pressure sensor, which sense a pressure applied thereon.
The haptic feedback is also provided at the touch pad of the mobile terminal.
FIG. 1 shows the structure of a conventional mobile terminal with a haptic feedback function.
As shown in FIG. 1, a touch pad 16 is elastically installed at a housing (not shown) of a mobile terminal through a spring 62.
And a piezoelectric actuator 64 is disposed at a lower side of the touch pad 16.
One portion 66 of the piezoelectric actuator 64 is coupled to the touch pad 16, and the other portion 68 thereof is coupled with a weight 70.
And when the one portion 66 of the piezoelectric actuator 64 is moved with respect to the other portion 68 thereof, the weight 70 is moved together with the other portion 68. The weight 70 is moved approximately along a z-axis. Since the weight 70 is not coupled to the housing, it can be moved freely.
The movement of the weight 70 along the z-axis generates an inertial force transmitted to the touch pad 16 through the piezoelectric actuator 64, and the touch pad 16 is moved along the z-axis due to the elastic coupling.
The movement of the touch pad 16 is sensed as a haptic sensation by a user contacted with the touch pad 16.
However, in a conventional haptic actuator 64, since the piezoelectric actuator 64 is operated in the state of being directly installed at the touch pad 16, the haptic feedback is occurred over the whole part of the touch pad 16, there is a limitation in locally implementing the haptic feedback at the touch pad 16, delicately.